This invention relates generally to fluid separators, and more particularly to an improved water polishing apparatus for removing oil and other flotsam from water. Removing oil and other flotsam from water is desirable and/or is required in many situations and for many different reasons. A typical situation is where oil has spilled on a body of water and has created an oil slick. In such situations, the slick and associated water is first removed and the oil is then separated from the water and salvaged or disposed of. In other situations, it might be desirable to remove from water, such flotable or semi-flotable materials as paper fibers, chopped vegetables, wood particles, or meat particles.
The separation of oil from water in which it has been mixed has presented particular problems which the prior art has sought to overcome by means of various special water polishing apparatus. Such apparatus have been characterized by means for directing and controlling the flow of mixed oil and water in predetermined courses which tend to cause the oil and water to separate and which include means for removing the separated oil from the water and for discharging and/or disposing of the oil and the water in some suitable or appropriate manner. Such apparatus have provided means for recirculating the water by being worked upon to extend the period of time it is worked upon in the apparatus and have provided means for aerating the oil and water mixture to enhance the tendency of the oil to rise in and separate from the water. Such apparatus have met with varying degrees of success, but to the best of our knowledge and belief, each is wanting in some material respect which has prevented or inhibited its commercial success.
With the limitations and deficiencies of known apparatus in mind, it is an object of the present invention to provide a water polishing apparatus which is particularly suitable, effective and efficient for removing flotsam from water. More particularly, it is an object to provide such apparatus for removing such materials as oil, paper fibers, wood particles, chopped vegetables and/or meat particles.
A further object is to provide such apparatus which contains novel flow control means for controlling the flow of a mixture of flotsam and water in a manner which is highly effective to cause the flotsam and water to be separate and which includes novel skimming means associated or in combination with the flow control means which is effective to skim flotsam from the surface of the water as it rises to and accumulates on the surface of said water.
Yet another object is to provide such apparatus which includes water recirculating means to recirculate a portion of the water through the apparatus, and novel means for removing or scavenging residual oil and/or mixed oil and water from the surface of the water flowing through the apparatus before it is discharged from the apparatus, for recirculation thereof through the structure for effective separation and removal of said oil.
Another object is to provide scavenging means of the general character referred to above which operates to draw in air and which mixes that air with the water and scavenged oil, preparatory to the recirculation thereof through the structure, whereby a volume of aerated oil and water effective for causing the separation of oil from water is introduced into the normal flow of fluids in the apparatus.
A further object is to provide such an apparatus which includes novel means for effectively distributing the aerated oil and water into the flow of fluid through the apparatus at predetermined spaced locations throughout the flow path of fluids in the apparatus.
Finally, it is an object of the present invention to provide apparatus for removing flotsam from water, which is simple, easy and economical to make, operate and maintain and which is highly effective, dependable and efficient in operation.
We have discovered that the above objects and advantages are achieved by means of an elongate tank with upstream and downstream ends, and an inlet at the upstream end for introducing a fluid and flotsam mixture into the tank to provide a mean fluid level therein. A plurality of longitudinally spaced, vertical dams extend transversally of the tank so as to divide the interior thereof into longitudinally-spaced zones. The dams have upper edges spaced below the mean fluid level in the tank. Each of the upstream zones is provided with a vertical weir which extends across the tank so as to divide the zone into an upstream section and a downstream section. Each weir has an upper portion which extends above the mean fluid level and a lower edge spaced above the bottom wall of the tank. Each of said weirs is preferably angularily positioned relative to the longitudinal axis of the tank whereby to converge with a side wall of the tank at an acute angle to provide a collecting corner for receiving flotsam.
The cross-sectional area of fluid flow over the dam is less than the cross-sectional area of fluid flow under the weirs whereby the flow over the dams is more rapid and turbulent than the flow under the weirs.
Skimming means are provided in the collecting corners of the upstream zones, to remove the flotsam from the surface of the fluid in said corners. One or more of the downstream collecting corners contains an open pipe below the surface of the fluid, and pump means are provided to cause a mixture of air, fluid and flotsam to be drawn into the open end of the pipe and be transported to various of the upstream zones for dispersion therein for further downstream flow.